1. Field of the Invention
The present invention relates generally to methods and apparatus for attenuating and/or baffling transient pressure waves in relatively incompressible materials in organs of the body, including, but not limited to the following systems of the human body: cardiovascular, pulmonary, renal/urological, gastrointestinal, hepatic/biliary, gynecological, central nervous, musculoskeletal, otorhinolaryngical and ophthalmic.
In one particular aspect, the present invention relates generally to the field of urology and gynecology, and in particular to the treatment of disorders of the urinary tract caused by sudden fluctuations of intravesical pressure. More specifically, in this aspect of the present invention, methods and devices are provided for the diagnosis and treatment of urinary disorders such as incontinence, urgency, frequency, interstitial cystitis, irritable bladder syndrome and neurogenic bladders.
2. Description of the Related Art
Pressure waves are known to propagate through incompressible fluids in various organs of the body. These pressure waves may be caused by a number of events including events within the body, such as a beating heart, breathing in the lungs, peristalsis actions in the GI tract, movement of the muscles of the body, or external events such as coughing, laughing, external trauma to the body, and movement of the body relative to gravity. As the elasticity of the surrounding tissues and organs, sometimes referred to as compliance, decreases, the propagation of these pressure waves increases. These pressure waves have many undesirable effects ranging from discomfort, to stress on the organs and tissue, to fluid leakage such as urinary incontinence, to renal failure, stroke, heart attack and blindness. accumulators and wave diffusers are types of devices that can modulate pressure waves in various nonanalogous settings. Accumulator technology is well known and used in hydraulic systems in aircraft, manufacturing equipment, and water supply and distribution since the 1940""s. Common types of accumulators include bladder accumulators, piston accumulators, non-separator (air over fluid), and weight loaded type accumulators.
Wave diffusers also affect the transmission of pressure waves in incompressible systems in various settings. The function of such diffusers is to interrupt the progress of a pressure wave and distribute the energy of the wave in so many directions so as to destroy the integrity of a uniform wavefront and its resultant effects. Wave diffusers may be used to protect a specified area from the impact of a wavefront.
Urinary tract disorders are a widespread problem in the U.S. and throughout the world, affecting people of all ages both physiologically and psychologically. Urinary tract disorders have a number of causes including birth defects, disease, injury, aging, and urinary tract infection.
In light of the foregoing, a number of attempts have been made to combat these disorders. One such attempt involves the use of an indwelling catheter connected to a collection bag with a clamping device on the catheter. Indwelling catheters, however, have a number of drawbacks. For instance, there is an infection risk associated with indwelling catheters, which provide a direct passage for bacteria or other microorganisms into the bladder. Thus, indwelling catheters can only be used for relatively short-term situations. In addition, indwelling catheters and associated collection bags are not cosmetically appealing to most patients.
An attempt at solving urinary incontinence involves the use of prosthetic urethral valves. One such prior art valve utilizes an inflatable cuff that is inserted around the outside of the urethra. The urethral valves of the prior art also have numerous disadvantages. One disadvantage of these valves is that they typically require surgery for installation, and some prior art valves must be operated externally and are therefore dependent on manual intervention.
The use of intra-urethral valves is also known. Typical intra-urethral valves of the prior art also generally require manual intervention. Another problem associated with prior art intra-urethral valves is that the valves may be displaced into the bladder or expelled from the urethra. There is also an infection risk associated with many such valves since they often extend into the meatus and/or have portions of the device external to the urethra providing a passage for microorganisms into the bladder.
Electrical stimulation therapy including rectal, intra-vaginal and external has been attempted to tone the muscles and stimulate nerves supporting the bladder and urethra. This therapy requires lengthy and numerous treatments, and any benefits derived from the therapy typically diminish when the treatments are stopped.
Current surgical incontinence procedures typically focus on the augmentation of urethral flow resistance. Prior art surgical interventions include bladder neck suspensions and bulk (collagen) injections. Although these procedures can be clinically effective with certain patients, problems include widely variable clinical outcomes, relative high costs to perform, potential complications related to surgery, and any effects may be short lived.
Drug therapy exists for a number of urinary tract conditions, including overactive bladder. These drugs include oral medications (systemic) and drugs delivered directly into the bladder. These drugs typically suffer from side effects, lack of effectiveness and high morbidity. Oral medications typically do not allow immediate relief of symptoms and include side effects such as dry mouth and constipation. Drugs delivered directly into the bladder often require continuous or intermittent catheterization for introduction of the therapeutic at the clinically appropriate time.
The intent of the treatment methods described to date either focus on the augmentation of urethral flow resistance, the temporary stoppage or absorption of all urethral flow, or relaxing the detrusor muscles to minimize unwanted contractions. The disadvantages and limitations of the prior art treatments are numerous and include:
an excessively high level of patient interaction is typically required to operate and/or maintain the devices, especially for elderly patients and for physically or mentally challenged patients;
limited clinical efficacy;
restricted urine outflow;
patient discomfort and side effects;
urethral and bladder infections related to the devices used; and
relatively expensive when compared to non-clinical solutions (diapers, pads, etc.).
These prior art approaches do not address the reduction in dynamic compliance which results in increased intravesical bladder pressure.
Embodiments of the present invention generally provide methods and devices for use within the body to measure and/or attenuate and/or manage pressure waves in incompressible fluids in organs and tissues of the body. Embodiment of pressure accumulators include either single units or multiple units of single or multichambered devices, diaphragmatic structures, bellows of various forms, and active and passive mechanical structures capable of managing energy, and instrumentation for the clinical use of the devices.
Particular embodiments of the present invention overcome the limitations of the above-described methods and devices for treating urinary tract disorders by increasing the effective dynamic compliance of the bladder or other anatomical structure or system by adding a compliant member to a semi- or non-compliant system. Methods and apparatus of embodiments of the present invention eliminate or reduce the symptoms of patients suffering from one or more of the symptoms of incontinence, overactive bladder, neurogenic bladder, frequency, urgency, interstitial cystitis, and other disorders of the urinary tract by reducing transient pressure changes including impulsive pressure spikes in the urinary tract due to a number of common actions such as coughing, jumping, laughing or sneezing. In addition, apparatus and methods of embodiments of the present invention minimize the possibility of patient suffering caused by patient retention, irritation or infection concerns. In addition, the apparatus and methods of the embodiments of the present invention can address multiple symptoms suffered by the same patient. In addition, devices and methods of embodiments of the present invention are simple and do not necessarily require cystoscopy to place and/or remove the devices.
There is provided in accordance with one aspect of the present invention, a method of attenuating pressure and/or deflecting pressure waves in an anatomical structure. The method comprises the steps of placing an attenuator in communication with a body cavity, and exposing the attenuator to a change in pressure within the cavity. The change in pressure is thereafter attenuated. Generally, the change in pressure is an increase in pressure. In one embodiment, the placing a step comprises placing the attenuator within the cavity. In one application of the invention, the cavity is within the bladder.
Preferably, attenuating the increased pressure is accomplished by a reduction in volume of the attenuator. The reduction in volume is preferably responsive to the increase in pressure. In one embodiment, the attenuator comprises a compressible wall which compresses in response to intravesical pressure to reduce the volume of the attenuator thereby attenuating intravesical pressure spikes.
In accordance with another aspect of the present invention, there is provided a method of treating stress or urgency incontinence, or other urinary tract dysfunction. The method comprises the steps of identifying a patient exhibiting symptoms of a urinary tract dysfunction, and positioning a compressible pressure attenuator in the patient""s bladder. The positioning step preferably comprises carrying the attenuator transurethrally into the bladder on a deployment device. The method may further comprise the step of removing the attenuator from the bladder. Preferably, the compressible pressure attenuator maintains the intravesical pressure below the urethral leak point pressure, which is generally within the range of from about 80 cm H2O or less to about 120 cm H2O.
In accordance with another aspect of the present invention, there is provided a device for treating urinary tract dysfunction. The device comprises a compressible attenuator having an expanded volume within the range of from about 10 cc to about 50 cc, which is compressible to no more than about 80% of its expanded volume under a pressure of about 80 cm H2O (range 80 cm H2O to 120 cm H2O). In one embodiment, the attenuator comprises an inflatable balloon. In an alternate embodiment, the attenuator comprises a compressible bellow. In either embodiment, the attenuator may further comprise a pressure transducer, and an inflation port. Embodiments provided with an inflation port are preferably additionally provided with a valve, for inflating the attenuator within the bladder.
In accordance with a further aspect of the present invention, there is provided a method of treating a patient. The method comprises the steps of providing a compressible attenuator which is movable from a first, introduction configuration to a second, implanted configuration. The attenuator is introduced into the body while in a first configuration, and it is transformed within the body to the second configuration. The attenuator thereafter attenuates a pressure spike within the body by reversibly reducing the volume of the attenuator in response to the pressure spike.
In one application, the introducing step comprises transurethrally introducing the attenuator into the bladder. The transforming step comprises at least partially inflating the attenuator. Alternatively, the transforming step comprises permitting the attenuator to transform under its own bias. Preferably, the attenuating step comprises reducing the volume of the attenuator by at least about 5%, preferably at least about 10%, and, if necessary to attenuate a pressure spike, by at least about 25%. The method may further comprise the step of removing the attenuator from the body.
In accordance with yet a further aspect of the present invention, there is provided a method of estimating the dynamic compliance of the bladder. The method comprises the steps of infusing a volume of liquid into the bladder, and measuring the intravesical pressure in the bladder. The infusing step may comprise infusing a volume of at least about 50 cc""s over a time of no more than about 10 seconds. In one application, the infusing step is accomplished through a first lumen of a catheter, and the measuring step is accomplished through a second lumen of the catheter.